1. Field of the Invention
The present invention relates to an image forming apparatus of the type having a sheet storing unit accommodating a sheet tray, which is movable between an operative position and an inoperative position, and an image forming unit removably mounted on the top of the sheet storing unit when in use.
2. Description of the Background Art
An image forming apparatus of the type described is known in the art and made up of a sheet storing unit and an image forming unit removably mounted on the top of the sheet storing unit when in use. The sheet storing unit includes a sheet tray loaded with sheet rolls. A sheet selectively paid out from either one of the sheet rolls is fed to the image forming unit. The sheet tray is selectively slidable into the sheet storing unit to an operative position or out of the sheet storing unit to an inoperative position in substantially the horizontal direction.
The conventional image forming apparatus of the type described has the following problem unsolved. When the image forming apparatus is newly purchased and installed at the user""s station or when it is moved to another place, the image forming unit is absent on the sheet storing unit. Assume that in such a condition a person pulls out the sheet tray loaded with the sheet rolls or loads the sheet rolls in the sheet tray pulled out. Then, a heavy moment of rotation ascribable to the sheet tray acts on the sheet storing unit and is apt to cause the sheet storing unit to falldown.
Technologies relating to the present invention are disclosed in, e.g., Japanese Patent Laid-Open Publication No. 6-242641.
It is an object of the present invention to provide an image forming apparatus capable of preventing a sheet storing unit thereof from falling down in the absence of an image forming unit due to a moment generated when a person pulls out a sheet tray loaded with sheets or replenishes sheets to the sheet tray pulled out.
An image forming apparatus of the present invention is generally made up of a sheet storing unit and an image forming unit removably mounted on the top of the sheet storing unit when in use. The sheet storing unit accommodates a sheet tray loaded with sheets and selectively movable into the sheet storing unit to an operative position or out of the same to an inoperative position. A locking mechanism inhibits the sheet tray from being moved to the inoperative position. An unlocking device unlocks the locking mechanism when the image forming unit is mounted to the sheet storing unit.